What is the nature of hearing loss in babies and children?
The nature of hearing loss in babies and young children depends on different factors. A baby may be born deaf, lose his or her hearing as a result of meningitis or an ear infection, or the cause may be hereditary. To understand that better, let’s have a look at the ear’s anatomy.
The ear has three parts:
- the outer ear is made up of the pinna (what you see on the outside of the head) and ear canal
- the middle ear comprises the eardrum, middle ear bones and Eustachian tube
- the inner ear is made up of the cochlea (organ of hearing), semi-circular canals (help with balance) and part of the auditory nerve
What are the types of hearing loss in babies and children?
Depending on the part of the ear that is affected, there are different treatment options:
- Conductive hearing loss is caused by problems in the outer/middle ear. There is an interference with the transmission of sound through the outer and middle ear, but sounds still reach the cochlea. Softer sounds will not be heard and sound quality may be compromised. This type of hearing loss can often be treated medically or surgically.
- Sensorineural hearing loss is caused by problems in the inner ear, including the cochlea and auditory nerve. Most common cause is damage to hair cells in the cochlea so that nerve cells cannot send signals to the brain. This is a permanent hearing loss and cannot be treated medically/surgically.
- Central hearing loss – sound is transmitted to the auditory nerve but it is not processed normally along the auditory nerve and/or in the brain.
What are the symptoms of hearing loss among babies and young children?
In order to prevent hearing loss in children you need to check if your child responses naturally as for their age. In order to do so, check the list below …..
|Birth||Is your child startled by loud noises?
Does your child coo and gurgle?
|3 months||Does your child smile when spoken to?
Does your child babble?
|6 months||Does your child turn towards the side where the sound is coming from?
Has your child started experimenting with sound?
|9 months – 1 year||Does your child look up when you call?
Does your child create “speech-like” sounds with single syllables strung together, da-da-da-da?
|1 – 2 years||Does your child understand simple phrases?
Does your child have a vocabulary of between 20 and 50 words and use short phrases? “no more” “daddy up”
|2 – 4 years||Does your child understand conversation easily?
Does your child use 2-3 word sentences?
|4 – 6 years||Does everyone who knows your child, think he/she hears well?
Is your child able to convey information and ask questions?
If you answered “NO” to any of these questions, it is highly recommended that you seek advice immediately. If you suspect that your baby or child doesn’t hear properly – get help right away. The first few years of a child’s life are when language is acquired. If he or she is not exposed to sound, speech will not develop naturally.
Early intervention is the key to enabling natural development of deaf and hard of hearing infants – but how early is early? Ideally the child should be screened by the age of one month and diagnosed by three months. Look out for tell-tale signs that your baby does not hear properly, and arrange to have him or her screened by an audiologist.
How will my child’s hearing be tested?
There are several different tests that may be conducted.
- Otoacoustic Emission Testing (OAE)
A small probe is placed in the child’s ear canal. A tone is sent into the ear and an echo is recorded from a healthy cochlea. Absence of an echo indicates a problem. This test requires no response from the child and is used as a screening procedure.
- Auditory Brainstem Response (ABR)
Electrodes that measure the brainstem’s electrical response to sound are attached to the child’s head. The tester then determines the softest sound that will get a response from the brainstem. Older children need to be sedated for this test as movement affects results.
- Behavioural Observation Audiometry (BOA)
Hearing is tested by watching for changes in the child’s behaviour in response to sound. A sound is presented through speakers and a response like a blink, smile or startle may be an indication that the sound was heard.
- Older children can be tested using Visual Reinforcement Audiometry (VRA): the child turns his or her head in response to a sound presented from a speaker and receives visual reinforcement, or Play Audiometry: the child responds to sound presented through earphones by playing a game, e.g. putting a peg in a board when they hear a sound, or Pure tone Audiometry: the child wears headphones and lifts his/her hand when a sound is heard.
Nicole da Rocha, Clinical Audiologist and Speech Pathologist